Technical Field
The present invention relates to a position-detecting device configured to detect positions of respective body parts of a sleeper using a body pressure distribution sensor including pressure sensors arranged in a matrix pattern. The present invention also relates to a respiration measurement device and a heart rate measurement device configured to detect a respiration measurement position and a heart rate measurement position of the sleeper using the position-detecting device to measure states of respiration and heart rate.
Background Art
There is known a sleeping apparatus configured to detect a body movement or a position of a sleeper and control reclining of a bed apparatus for a sit-up action of the sleeper on the basis of a detection result (see Japanese Patent No. 3321942 given below).
In the disclosed sleeping apparatus, pressure sensors arranged in a plane in the bed apparatus figure out a pressure distribution (constant pressure lines) of an entire body of the sleeper, then portions which receive large loads and correspond to centers of a body trunk of the sleeper are connected from a head portion to a leg portion, so that a shape of a sleeper's sleeping posture is determined.
Depending on the sleeping posture, a portion receiving a highest pressure at both ends of a line connecting the head portion and the leg portion respectively is determined to be a lower back, and the reclining of the bed apparatus is driven with the position of the lower back determined in this manner as a supporting point (see [0017], [0019], FIG. 2 to FIG. 4 of Japanese Patent No. 3321942).
Further, there is known a sleep monitoring apparatus configured to specify positions of respective body parts of a body in order to determine whether it is REM sleep or not on the basis of the number of body movement within a predetermined time (see Japanese Patent Application Publication No. 2000-316832 given below).
In the sleep monitoring apparatus, a sensor sheet having pressure-sensitive elements at a predetermined distribution is set on a bed. Characteristic amounts of the respective load distributions of the entire body in respective sleeping postures are recorded in a memory of a controller. The controller processes load signals from the respective pressure-sensitive elements of the sensor sheet, binarizes the load distributions of the whole, and obtains the characteristic amounts.
The controller collates the characteristic amounts of the respective load distributions in the memory and the characteristic amount of the load distribution of the sensor seat to detect a current sleeping posture of a user. The controller specifies positions of respective body parts (head portion, lower back portion, leg portion, both hands) on the basis of the detected sleeping posture, and when the specified positions are changed, counts the number of the changes (see [0022] to [0033] and FIG. 1 and FIG. 3 of Japanese Patent No. 3321942).